Hydropneumatic flushing cisterns



Sept. 16, 1969 R. BoccARD HYDROPNEUMATIC FLUSHNG CISTEQRNS 4 Sheets-Sheet 1 Filed Nov. 4, 1966 |131.. I., JI

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Sept. 16, 1969 R. aoccARD HYDROPNEUMATIC FLUSHING CISTERNS 4 Sheets-Sheet 2 Filed NOV. 4. 1966 if l l Sept. 16, 1969 l R, BOCCARD 3,466,673

HYDROPNEUMAT IC FLUSHING C I STERN S Filed Nov. 4. 1966 4 Sheets-Sheet :5

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Sept- 16, 1969 R. BQCCARD 3,466,613

HYDROPNEUMATIC FLUSHING CISTERNS Filed Nov. 4. 1966 4 Sheets-Sheet 4 United Statesl Patent O 3,466,673 HYDROPNEUMATIC FLUSHING CISTERNS Ren Boccard, 100 Cours Fauriel, St.-Etienne, France Filed Nov. 4, 1966, Ser. No. 592,057 Claims priority, application France, Nov. 9, 1965, 9,319; June 3, 1966, 9,478 Int. Cl. E03d 1/34 U.S. Cl. 4-52 20 Claims ABSTRACT OF THE DISCLOSURE tion, biasing means urging the closure member away from Y the open position towards the closed position, a cover for the valve closure member, portions of which together with the valve closure member define a chamber, a duct communicating with the chamber to lead water thereto and a flow-producing means to produce a flow of water from the chamber so as to cause the upward force on the closure member to exceed the downward force on same and open the closure.

According to the present invention, there is provided a hydro-pneumatic flushing cistern, comprising a container, portions of said container defining a water inflow port for feeding water to the interior of said container, a valve seat at the base of said container bounding a water outow port of greater through-flow area than is said inow port for leading flushing water from said container, a valve closure member in said interior movable kbetween a closed position in which it contacts said seat and closes said outflow port and an open position which is above said closed position, biasing means urging said closure member away from said open position and towards said closed position, a cover covering said valve closure member, portions of said cover and said valve closure member defining therebetween a chamber, duct means communicating with said chamber for leading water thereto, and flow-producing means for producing a flow of water from said chamber such as to cause the upward force on said closure member to exceed the downward force on said closure member, whereby said closure member is opened.

In order that the invention may be clearly understood and readily carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:

FIGURE 1 is a fragmentary vertical axial section through a hydro-pneumatic flushing cistern of a watercloset, with a pilot valve and a water outflow valve in closed conditions;

FIGURE 2 is a detail of FIGURE 1, but illustrates a first stage in the initiation of the flushing operation;

FIGURE 3 is a fragmentary section taken on the line 3-3 of FIGURE 2;

FIGURES 4 and 5 are similar views to FIGURE 2, but illustrate respective second and third stages in the initiation of the flushing operation;

FIGURE 6 is a view similar to FIGURE 1, but showing a first modified version of the cistern;

FIGURES 7 and 8 are a detail of FIGURE 6, but illustrate respective stages in the initiation of the flushing operation;

3,466,673 Patented Sept. 16, 1969 ice FIGURE 9 is a view similar to FIGURE 1, but showing a second modified version of the cistern;

FIGURE 10 is a fragmentary, vertical, axial section through a water outfiow valve and an opening device therefor in a third modified version of the cistern;

FIGURE 11 is a fragmentary, vertical axial section through a modification of the opening device;

FIGURE 12 is a section taken on the line 12-12 of FIGURE 11;

FIGURE 13 illustrates a fragmentary, vertical axial section through a fourth modified version of the cistern, with a water outow valve closed;

FIGURE 14 is a view similar to FIGURE 13, but with lthe water outflow valve open;

FIGURES 15 and 16 are views similar to FIGURE 13, but of fifth and sixth modified versions of the cistern; and

FIGURE 17 is a view similar to FIGURE 1, but of a seventh modified version of the cistern.

Referring principally to FIGURES 1 to 5, the cistern includes a substantially fluid-tight container 1 which, in he -example illustrate-d, is `cylindrical and has a top wall The base wall of the container 1 could be welded to the bottom of the side wall of the container, or could be separate therefrom and fixedtherein as will now be described.

Secured to the inner periphery of the bottom of the side wall is an inverted annular channel-form member 2 the upper portion 2a of which is curved to receive and centre a compressible toroidal packing 3. The base wall 4 (see FIGURE 9) of the container includes a planar wall portion 4a (see FIGURE 6) which is laterally integral with a sloping annular Wall portion 4b which at its outer periphery is integral with a curved, annular, channel-form, wall portion 4c which, with the portion 2a, bears in a fluid-tight manner against the packing 3. The pressure of the base wall 4 against the packing 3 is produced by an externally screw-threaded ring 5 screwed into an internally screw-threaded lower portion of the member 2. Instead of the ring there may be used a circlip disposed, after compression of the packing 3, in a circular groove in the member 2 extending under the portion 4c.

Centrally, the wall 4 is formed with a large-dimension aperture permitting the insertion and securing therein, by welding or the like, of a flushing pipe 6 (see FIGURE 4), whereas laterally a water inflow port 7, of a smaller through-How area than is the water outflow port at the top of the pipe 6, debouches through the sloping wall portion 4b.

Internally, the container 1 is provided with a cover 8 the lower edge of the side wall 8a (See FIGURE 6) of which bears on the planar wall portion 4a.

The cover 8 is for example of cylindrical shape and is positioned on the wall 4 by means of peripheral projecting tongues 8c fitted or directly formed on the side wall 8a at pre-determined angular spacings. The tongues 8c may be resiliently engaged or otherwise secured in studs 4d fitted or directly formed on the portion 4b and corresponding in number and annular spacing to the tongues 8c.

In the example shown, this positioning is effected by means of three tongues 8c engaging in three corresponding studs 4d distributed at an angular spacing of 120.

In the lower portion of the side wall 8a are cut apertures 8d which are circular in the example illustrated, and are uniformly spaced apart at the same level and provide communication between the interior of the container 1 outside the cover 8 and the interior of the cover 8.

Within the cover 8 commences the pipe 6 the widened initial portion of which provides the water outflow port and a frusto-conical valve seating 6a with which cooperates a corresponding truste-conical portion 9a of a valve closure member 9 centered in the cover 8.

The valve closure member 9 is manufactured from a ilexible or semi-rigid material, for example plastics material or rubber. Axially, it has extending through it a cylindrical hole receiving a conduit 10 of corresponding shape on which the member 9 is arranged to slide, preferably in a uid-tight manner. Peripherally, the member 9 has a triangular cross-section a vertical tace 9b of which is parallel to the side Wall 8a leaving between the face 9b and the side wall a clearance e permitting passage of water between the chambers c1 and c2 formed within the cover 8 respectively below and above the cover 8.

A compression spring 11, mounted between the top wall 8b of the cover 8 and the top face 9c of the valve closure member 9 tends to urge the valve closure member against the seating 6a of the pipe 6 which the member 9 thus closes in a uid-tight manner.

Various pilot means may be provided for bringing about an outow of the water contained in the chamber c2, in such manner as to diminish the downward force exerted on the valve closure member 9, this causing the opening of the valve closure member and resulting in the sudden freeing of the outiiow port for the water contained in the cistern and, consequently, in the desired flushing effect. This pilot means may consist of a simple cock, or a lever with a valve closure member.

However, this pilot means preferably consists of a plungentype valve requiring the application of a small thrust force to bring about the initiation of the flushing action. Accordingly, the plunger-type valve includes a plunger button 12 centered and freely slidable in a bear* ing face 13a of corresponding crosssection formed in one end of a sleeve 13 which is radially fixed in the pipe 6. At its other end, the sleeve 13 is provided axially with a chamber 13b the peripheral wall of which has extending through it cylindrical perforations 13C which establish communication between the chamber 13b and the pipe 6. The button 12 has iixed thereto co-axially a plunger rod 12a which is guided and slides in a Huid-tight manner in a packing 14 disposed at the inner end of the chamber 13b of the sleeve 13. At its end opposite to the button 12, the rod 12a carries two valve closure members in the form of frusto-conical lips 12b and 12e which increase in diameter in respective opposite axial directions. The valve lips 12b and 12C extend axially through a pilot valve closure member 15 the aperture 15a in which they are arranged to close alternately. The lip 12b is ycontinually urged against the member 15 by a spring 16 mounted between the lip 12b and the outer end face of a chamber 17a of a plug 17 which is secrewed into an internally screwthreaded sleeve 18 secured, by welding or the like, in the pipe 6 at a location diametrically opposite to the sleeve 13. Co-axially relatively to the double valve and the member 15 there are formed two chambers c3 and c4, which are provided by forming the lower end of the conduit 10 with two envelopes or cylindrical and co-axial walls 10a and 10b perpendicular to the conduit 10.

The action of the spring 16 on the double valve tends to maintain the button 12 in a projecting position, to maintain the aperture 15a closed by the lip 12b of the double valve, and to maintain the member 15 abutted against the free circular end of the wall 10b which acts as the pilot valve seat, the result of this being to separate the chamber c4 from the chamber c3 and the conduit 10. Furthermore, the member 15, centered in the chamber c3, is provided at its outer periphery with a triangular lip 15b a horizontal face 15c of which is parallel to the cylindrical wall 10a, leaving between it and the wall a clearance e1 permitting communication between the conduit 10 and the chamber 17a.

It will be clear that, in the version of FIGURES l to 5, the pilot means is mounted at the base of the cistern and directly in the pipe 6. However, the pilot means may also be mounted at other points, for example in the case of a cistern disposed at a relatively low level, at the upper part of the container as shown in FIGURES 6 to 8. In this version, the functioning of the ushing cistern is identical and the main features of the cover 8 mounted on the base wall 4, the pipe 6, the seating 6a thereof, the valve closure member 9 and the spring 11 are again present. However, the pilot valve has a cylindrical sleeve 19 of large dimensions for housing the parts of the valve. The sleeve 19 is secured in any known manner to the upper part of the container 1 and, preferably, to the centre of the top wall 1a, as shown. Internally, the sleeve 19 has a smaller co-axial sleeve 20 forming the chamber c4 and having communication perforations 20a. A partition 21 having a sealing packing 21a separates the chamber c4 and the chamber c3 formed at the closed lower end of the sleeve 19. The same arrangement as in the version of FIGURES 1 to 5 is provided in repect of the plunger button 12, the plunger rod 12a, the double valve, the spring 16, and the pilot valve closure member 15. However, the conduit 1t) now extends upwards from the cover 8y to establish communication between the chamber c2 and the chamber c3 formed below the member 15. An auxiliary conduit 22 leads from the chamber c4 to the pipe 6 to permit the partial evacuation of the water contained in the sleeve 19. A description will now be given of the operation of the two versions already described.

The water is admitted into the container 1 through the inflow port 7. The water lills the container up to the point of equilibrium between the water pressure and the pressure of the air cushion compressed in the upper part of the container.

Through the apertures 8d, the `water penetrates into the cover 8 and provides opposing upward and downward pressures on the member 9, the spring 11 maintaining the member 9 closed on its seating 6a. The water also flows through the conduit 10 into the chamber c3. The water lls the chamber and, as it flows about the pilot valve closure member 15, provides opposing axial pressures on the member 15 which is maintained in its closed position owing to the spring 16 acting on the double valve which, by means of its lip 12b, closes the axial aperture 15a. Thus, the filling of the cistern is effected (FIGURES 1 and 6).

On exertion of pressure on the button 12, the lip 12b of the double valve is urged away from the aperture 15a against the action of the spring 16 (FIGURE 2). The water contained in the chamber 17a is able to ow, via the aperture 15a into the chamber c4 and, via the apertures 13e, or 20a, into the pipe 6.

As soon as this iiow commences, the resultant force on the member 15 is reversed in direction, so that the pilot valve is opened, the pressure of the water in the conduit 10 urging away from the pilot valve seat the pilot valve closure member 15 the axial aperture 15a in which is now blocked by the lip 12e of the double valve (FIGURES 4 and 7), and the water flows under greater pressure into the pipe 6. In this manner, the water contained in the chamber c2 above the main valve closure member 9 is evacuated and an upward resultant force is established on the member 9, so that the latter is raised against the action of the spring 11 (FIGURES 5 and 8). The ushing then takes place, with considerable force, via the pipe `6.

At the end of the liushing operation, the resultant force on the member 9 is downward and urges the member 9 against its Seating 6a whereupon the container 1 is re-iilled.

A notable advantage of a control arrangement of this kind, operating by two successive elects involving differential pressures, will be readily apparent in that a slight pressure on the push button sutlces to open the main valve which is however subjected to the considerable pressure of the water in the container.

A further advantage of the cistern resides in its silent operation, notably during lling, since the inflow 0f water through the port 7 is eiected directly, without constriction, and therefore without prolonged whistling There is always a small quantity of water in the bottom of the container, so that spurts entering the container from the port 7 are damped. This direct, unconstricted inflow of water is rendered possible because the main valve closure member is protected from turbulence and guided yand retained by the cover 8. It will be noted that, as indicated in chain lines in FIGURE 1, the container 1 may contain a flexible diaphragm R which improves the silent operation of this ilushing system. The diaphragm R is connected in a substantially uid-tight manner at its periphery to the botom of the side wall of the container round the whole circumference of the side wall.

Further versions of the pilot valve and its controls will now be described with reference to FIGURES 9 to 12.

Referring to FIGURE 9, a vertically slidable rod 23 is mounted in a fluid-tight manner in a tube 24 secured in any known manner to the centre of the top Wall of the container 1 'and of the cover 8. In its upper end, the tube 24 has a sealing and guiding packing 24a through which extends axially the rod 23 the upper end of which is visible above the container and carries a grasping ring '23a permitting the manual opening of the pilot valve. At its lower end, the tube 24 opens into the chamber c2 through the flat top wall 8b of the cover 8 to which the tube is iixed in any known manner. Formed in the lower end of the tube 24 is a bulge 24b constituting a chamber c5 in which is disposed packing 2-5, which may be of the stuffing box type for example having on each face a metal washer 25a. A compression spring 26, the upper end of which bears on the lower washer 25a, bears at its lower end on la washer 27a secured on the rod 23 above a pilot valve closure member 27 carried at the lower end of the rod 23. The member 27, which is for example of frusto-conical `shape as shown, thus closes an `axial hole 9d of circular cross-section extending through the member 9. As will be clearly understood, the action for initiating the flushing operation consists of a simple pull in the direction of the arrow F on the rod 23 to cause the member 27 to open and permit the preliminary flow through the hole 9d of the water contained in the upper chamber c2, whereby an upward resultant force on the member 9 then opens the latter.

FIGURE shows a version in which the opening means for the pilot valve is directly mounted on the pipe 6. Iu'this version, the member 9 centered in the cover 8 has extending axially through its hole 9d a slidable thrust rod 28 the upper end of which carries the pilot valve closure member 27. The member 27 is urged to close the h old 9d by a compression spring 29 mounted between the horizontal top wall 8b and a washer 30 secured to the rod 28 above the member 27. At its lower end, the rod 28 is guided by any suitable device, such as a ring 31 carried in the pipe 6 by radial bars `so as not to hinder significantly the water flow. The lower extremity of the rod 28 bears continually, under the action of .the spring 29, against an eccentric cam 32 fast with a turnable shaft 33 diametrically mounted in the pipe 6. The turning of the shaft 33 is manually performed by means of an arm 34 xed to the end of the shaft 33 outside the pipe 6, the bearing faces of the shaft 33 in the pipe Wall being rendered iiuid-tight in any known manner, Turning of the arm 34 in the direction of the arrow F results in an angular displacement of the cam 32 which produces an upward thrust on the rod 28 to raise the member 27 and cause the flushing to occur.

IReferring to FIGURES 11 and 12, in the modication the lower extremity of the thrust rod 28 bears in an eccentric groove 35o.` formed in the middle portion of a cam shaft 35 extending through the pipe 6, the cam thus being a cylindrical portion of the shaft having its axis parallel to the axis of rotation of the shaft. The shaft 35 is here Iagain turnable by the external arm 34.

In the versions of FIGURES 13 to 17, the main valve closure member 9 is no longer mounted for sliding in the cover 8, but has its annular portion 9e projecting laterally beyond the seat 6a of a thickness which is such that the member 9 is suiciently strong and yet may exhibit a degree of flexibility permitting, under the action of water pressure exerted upwardly or downwardly, deformation of the portion 9e in the manner to be described. The outer periphery 9j of the annular portion 9d is xed by any appropriate means, and in a Huid-tight manner, on a ring 39, the arrangement being such as to tend to maintain the member 9 in its closed position on the seat 6a. Above the member 9 is a cover 37 the top wall 37b of which is formed with a water inlet opening 37c. The throughflow area of the opening 37e is changeable by for example tting therein, during assembly of the cistern, a bush 38 from a number of bushes of differing diameter, the selected bush 38 having a diameter corresponding to the Water supply pressure. Any other suitable means 37e may be utilised. The cover 37 bounds, above the member 9, the chamber c2 receiving the necessary volume of Water via the opening 37C, in such manner that a pressure giving huid-tight closure is exerted by the member 9 on the seat 6a. It should be emphasised that the throughflow area of the opening 37e is substantially less than that of the outow conduit 10, so that, during the initiation of the ilushing operation, there is obtained in the chamber c2 a lower pressure than that below the downwardly facing surface of the annular portion 9e.

In the version shown in FIGURES 13 and 14, the periphery 9f of the valve is provided with an upwardly and inwardly directed annular lip portion to form an annular seating 9g in which is engaged in a fluid-tight manner a laterally outwardly directed annular flange portion 37a of the cover 37. The latter is made for example from stamped sheet-metal.

The assembly comprising the member 9 and the cover 37 is centered by the periphery 9f in the circular ring 39 the inside 39a of which enables the water pressure to be exerted upwardly against the portion 9e. If necessary, depending on the mode of assembling the cistern, the cover 37, the member 9 and the ring 39 may be assembled by means of screws or the like.

The ring 39 may for example be carried by legs 40 appropriately distributed and secured to the ring which is at a suitable distance from the base Wall 4. The legs 40 may bear freely on the Wall 4. However, it is also possible to secure permanently the legs 40 to the wall 4, for example by welding. The ring 39 may also be carried in any suitable manner, with appropirate spacing, above the base wall 4.

The initiation stages of the flushing operation are basically identical with those previously described. When the push button 12 is pressed, there is produced a ow of the water contained in the chamber c2 through the conduit 10. Owing to the difference between the inflow and outflow areas for the chamber an upward resultant force is produced on the member 9, as indicated by the arrow F1, deforming the member 9 which is thus raised from the seat 6a and opens the water outflow port through which the water in the cistern is evacuated. At the end of evacuation of the cistern, the water again enters the cistern through the port 7 and also enters the chamber c2 through the opening 37C, in such manner as to till the chamber c2 under a pressure ensuring the closure of the pipe 6 as already described.

FIGURE 15 shows a version in which the cover has a side integral with the ring. This cover 41 includes a vertical cylindrical tube receiving at its bottom in a fluid-tight manner the circular periphery 9j of the member 9, the tube being closed at its upper end either by means of a separate itted plate 41a, xed in any suitable manner, or by a top wall integral with the tube.

FIGURES 16 and 17 show applications to the cistern 7 of FIGURE 13 of the pilot Valves and controls therefor already described with reference to FIGURES 6 and 10.

Referring to FIGURE 16, the evacuation of the chamber c2 is achieved by means of the arm 34 acting via the cam 32 on the push rod 28 carrying at its free end the pilot Valve closure member 27 maintained by the spring 29 in a position closing the hole 9d formed in the member 9. It will be recalled that this device can instead include a slidable rod extending through the top wall of the container.

FIGURE 17 shows the pilot valve operable by means of a push button and mounted in the upper part of the cistern.

In the versions of FIGURES 13 to 17, owing to the resilient exibility of the main valve closure member, it becomes possible to dispense with the compression spring provided in the previous versions and mounted in the cover. However, it is also possible to retain this spring, so as to obtain a more rapid return of the closure member after flushing.

In the versions of FIGURES 13 to 17, the base wall 4 is a stamped circular annulus the annular outer peripheral edge portion of which is turned down for resilient engagement in the bottom of the side wall of the container 1. The wall 4 may be secured to the side wall of the container by spot welding or by seam welding of the contiguous edges at s. Fluid-tightness of the peripheral joint is achieved by internally fitting the joint with a packing made of for example poured plastics material, or any other suitable packing. The pipe 6 is hard-soldered, at 4a, into the central aperture in the wall 4.

The ushing cistern has at its upper part, preferably in the top wall 1a, a non-return valve which, in the example illustrated in FIGURE 17, includes a hollow casing 36 secured by hard-soldering or other means in the top wall 1a of the container 1. Within the casing 36, a ball 36a is urged by a compression spring 36h against a corresponding seat formed in the upper portion of the casing 36. A port 36C, closable by the ball 36b, establishes communication between the interior of the container 1 and the ambient atmosphere. This non-return valve permits the automatic replacement of any air which may escape during the ushing action. In fact, at the end of the evacuation of water, a suction eect is set up in the container which causes a small inflow of air through the non-return valve, thus making it possible to maintain within the container a volume of air sufficient to produce the flushing effect.

I claim:

1. A hydro-pneumatic flushing cistern, comprising a container, portions of said container defining a water inow port for feeding water to the interior of said container, a valve seat at the base of said container bounding a water outflow port of greater through-ow area than is said inow port for leading flushing water from said container, a valve closure member in said interior movable between a closed position in which it contacts said seat and closes said outow port and an open position which is above said closed position, biasing means urging said closure member away from said open position and towards said closed position, a cover covering said valve closure member, portions of said cover and said valve closure member defining therebetween a chamber, duct means communicating with said chamber for leading Water thereto, said duct means comprising other portions of said closure member and said cover defining therebetween a lateral clearance, and portions of said cover below said lateral clearance bounding aperture means upstream of said clearance with respect to water ow to said chamber; and flow-producing means for producing a ow of water from said chamber such as to cause the upward force on said closure member to exceed the downward force on said closure member, whereby said closure member is opened.

2. A cistern according to claim 1, and further comprising a projecting portion of said closure member projecting laterally outwardly beyond said seat and providing a downwardly facing surface for the application of an opening force on said closure member by water in said container.

3. A cistern according to claim 1, wherein said flow-producing means comprises conduit means leading from said chamber and a pilot valve in said conduit means operable to permit flow of water from said chamber via said conduit means.

4. A cistern according to claim 3, wherein said pilot valve comprises a pilot valve housing, a pilot valve seat in said housing encircling a pilot valve port, a pilot valve closure member in said housing movable between a closed position in which it closes said pilot valve port and an open position, portions of said pilot valve closure member defining an aperture therein, an opening plunger extending through said aperture and movable longitudinally to a limited extent relatively to said pilot valve closure member for displacing said pilot valve closure member from its closed position to its open position, third and fourth valve closure members provided on said plunger and operable to close alternately said aperture, and pilot valve biasing means urging said pilot valve closure member away from its open opsition and towards its closed position, said pilot valve closure member having its side remote from said pilot valve seat exposed to the pressure in said chamber when in its closed position.

5. A cistern according to claim 3, and further comprising a flushing pipe leading downwardly from said water outflow port and having said pilot valve mounted therein, said conduit means opening into said pipe.

6. A cistern according to claim 3, and further comprising a top wall of said cistern having said pilot valve mounted therein, and a manually operable opening member of said pilot valve extending upwardly through said top wall, said conduit means extending from said chamber to said water outflow port via said pilot valve.

7. A cistern according to claim 3, whe-rein said conduit means comprises portions of said closure member defining a hole therethrough communicating said chamber with said water outiiow port, and said pilot valve comprises a pilot valve closure member movable between a closed position in which it closes said hole and an open position above its closed position, pilot valve biasing means urging said pilot valve closure member away from its open position and towards its closed position, and pilot valve opening means operable to open said pilot valve closure member.

8. A cistern according to claim 7, and further comprising a top wall of said container, said pilot valve opening means comprising a longitudinally slidable member extending upwardly through said top wall and having said pilot valve closure member attached thereto.

9. A cistern according to claim 7, and further comprising a flushing pipe leading downwardly from said water outow port, said pilot valve opening means comprising a longitudinally slidable member extending downwardly through said hole and of a cross-sectional area at said hole less than that of said hole and having said pilot valve closure member attached to the upper end thereof, a cam shaft turnably mounted in said flushing pipe, a cam provided on said cam shaft and `co-operating with the lower end of said longitudinally slidable member for displacing the latter upwardly to open said pilot valve closure member, and an arm outside said pipe and said container and connected to said cam shaft for turning said cam shaft to turn said cam.

10. A cistern according to claim 9, wherein said cam comprises a substantially cylindrical surface portion of said shaft having its axis substantially parallel to the axis of turning of the shaft.

11. A cistern according to claim 1, wherein said biasing means comprises a exible annular projecting portion of said closure member projecting laterally outwardly beyond said seat round the whole circumference of said seat and providing a downwardly facing surface for the application of an opening force on said closure member by Water in said container, said cistern further comprising a ring in said container stationary relative to said container and closely encircling the outer periphery of said projecting portion and having said outer periphery xed thereto, and portions of said ring and the base wall of said container defining aperture means therebetween for permitting access of water to said downwardly facing surface, said cover extending to the region of said outer periphery and being connected to said outer periphery in a substantially Huid-tight manner round the whole of said outer periphery.

12. A cistern according to claim 11, wherein said duct means extends through said cover and is of a changeable through-How area.

13. A cistern according to claim 12, and further comprising an opening through said cover leading to said chamber, said duct means comprising a bush removably tted in said opening for interchanging with another bush removably ttable in said opening to change the throughflow area of said duct means.

14. A cistern according to claim 11, and further comprising supporting means attached to said ring and resting freely in said base wall and thus supporting said ring on said base wall.

15. A cistern according to claim 11, wherein said cover has a side wall integral with said ring round the entire circumference of said ring.

16. A cistern according to claim 15, wherein said cover has a top wall separate from said side wall but tted thereto in a substantially iluid-tight manner.

17. A cistern according to claim 11, and further comprising an upwardly and inwardly directed annular lip portion of the Valve closure member in the region of said outer periphery, and a laterally outwardly directed annular flange portion at the periphery of said cover engaged between said resilient annular projecting portion and said annular lip portion.

18. A cistern according to claim 1, wherein the base wall of said container is separate from the side wall thereof, said cistern further comprising an inverted annular channel-form member iixed in a iluid-tight manner round the inner periphery of the bottom of said side wall and projecting inwardly over said base wall, an annular packing extending in said channel-form member round the whole circumference thereof, and compressed between said channel-form member and said base wall, and clamping means maintaining said base wall pressed against said packing.

19. A cistern according to claim 1, wherein the base wall of said container is separate from the side wall thereof, said cistern further comprising a turned-down annular peripheral portion of said base wall adjacent to the bottom of said side wall and resiliently engaged in said bottom of said side wall, a weld securing said annular peripheral portion to said side wall, and an annular packing interposed in a substantially fluid-tight manner between said annular peripheral portion and said bottom of said side wall and extending round the whole circumference of Said annular peripheral portion.

20. A cistern according to claim 1, wherein said container is substantially iluid-tight and has a top wall, said cistern further comprising a pre-loaded, non-return valve mounted in said top wall for automatically admitting air to compensate for loss of air from the interior of said container during the outllow of flushing water.

References Cited UNITED STATES PATENTS 580,208 4/ 1897 Cahill 4-47 2,087,099 7/ 1937 Tilden 4--52 2,996,727 8/ 1961 Rose 4-52 FOREIGN PATENTS 1,256,574 2/1961 France.

PATRICK D. LAWSON, Primary Examiner 

